Comparison of Lightning Activity and NOx Distribution in the Upper Troposphere in China
中国地区闪电和对流层上部NOx的时空分布特征及其相关性分析

In order to understand the contribution of lightning to the abundance of NOx in the upper troposphere, the characteristics of spatial and temporal distribution of NOx in the upper troposphere and lightning in China, and the relationships between them are analyzed in this paper. The lightning data (from April 1995 to December 2005) and the NOx data (from October 1991 to November 2005) are obtained from the Global Hydrology Resource Center (GHRC), USA and the Halogen Occultation Experiment (HALOE) boarded on the Upper Atmosphere Research Satellite (UARS), respectively. It is found that lightning activities are in very good agreement with NOx volume mixing ratio in seasonal variations, annual variations, and spatial variations. The results prove that lightning is an important source of NOx in the upper troposphere. The height of the extreme value of NO is at about 350 hPa, while that of NO2 is at about 250 hPa. Intra-cloud lightning-generated NO is the main reason for the extreme value, the NO will oxidize into NO2 during the transmission process, and NO2 will be transported to higher height through the thunderstorms. Strong convective is helpful to transport NOx to the upper troposphere, while NOx generated by human activities can hardly do this. Therefore, in the area that more lightnings occur, the extreme value is bigger and its height is higher.